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THE  ANATOMY 
OF  THE  PEEITOI^^UM 


THE 

ANATOMY  OF   THE 
PERITONEUM 


1 

BY 


FRANKLIN  PEXTER,  M.  D. 

ASSISTANT   DEMONSTRATOR   OF   ANATOMY,    COLLEGE    OF   PHYSICLAJfS 
AND   SURGEONS    (COLUMBIA   UNIVERSITY)    NEW   YORK 


WITH  THIRTY-EIGHT  ILLUSTRATIONS 


NEW    YORK 
D.   APPLETON   AND   COMPANY 
1892 


Copyright,  1892, 

bt  d.  appleton  and  company. 


QMS&7 


PREFACE. 


From  my  experience  in  the  dissecting-room,  there 
seems  to  me  to  be  no  part  of  anatomy  which  is  quite 
so  unsatisfactory  or  incomprehensible  to  the  student 
as  the  peritonaeum.  It  is  impossible  to  offer  an  expla- 
nation of  why  anatomical  conditions  present  them- 
selves as  we  find  them,  but  in  some  cases,  at  least,  we 
can  explain  how  such  conditions  are  produced,  and 
if  one  understands  this  his  knowledge  is  of  a  more 
satisfactory  kind,  and  does  not  degenerate  to  a  mere 
matter  of  memory.  Moreover,  if  one  follows  the  de- 
velopment of  the  organs,  and  is  able  to  understand 
the  changes  produced  in  the  abdominal  cavity  by  this, 
he  not  only  gains  valuable  information  as  to  their 
normal  position,  but  can  more  easily  understand  the 
abnormities  that  occur.  There  is  no  way  of  obtain- 
ing a  clear  idea  of  the  peritonaeum  except  through 
a  knowledge  of  its  development.  It  is  this  belief 
which  suggested  to  me  the  writing  of  this  pamj^hlet. 
The  matter  contained  in  it  is  not  original  in  any  sense 
of  the  word. 


6  ANATOMY  OF  THE  PERITONEUM. 

I  believe  it  was  Prof.  Toldt,  of  Vienna,  who  first 
gave  tbe  true  description  of  the  development  of  the 
peritonseum.  His  article  was,  of  course,  written  in 
German,  and  therefore  is  useless  to  most  of  our  stu- 
dents. It  seemed  to  me  that  if  one  should  take  his 
description  as  a  basis,  make  many  more  plates  than  he 
gives  in  his  work,  and  so  take  the  student  along,  step 
by  step,  in  the  most  elementary  way,  he  would  not  only 
be  able  to  follow  the  description  with  comparative 
ease,  but  in  the  end  would  have  an  understanding  of 
the  subject.  It  is  with  this  idea  that  this  pamphlet  is 
offered  to  students  of  anatomy.  To  those  further  ad- 
vanced in  the  science,  the  sketches  will  seem  far  too 
diagrammatic  to  coincide  with  accuracy — and  I  agree 
with  them — but  I  have  tried  to  keep  the  main  object 
in  view,  namely,  that  it  is  not  the  embryological  de- 
tails which  the  student  is  trying  to  learn,  but  their 
result.  For  this  reason  it  has  been  made  most  dia- 
grammatical, with  the  hope  that  he  will  more  easily 
be  enabled  to  follow  each  step  in  the  development. 
There  is  much  in  regard  to  the  development  of  the 
liver  and  diaphragm  which  is  not  understood,  and 
therefore  the  simplest  possible  explanation  has  been 
chosen.  Even  though  in  some  details  it  be  incor- 
rect, it  may  aid  the  student  in  obtaining  an  idea 
of  the  peritoneal  connections  between  the  organs. 
Should  this  pamphlet  give  the  required  aid,  its  object 
will  have  been  accomplished. 


PKEFACE.  7 

I  would  here  express  my  sincere  thanks  to  Prof. 
C.  S.  Minot,  of  Harvard  University,  as  well  as  to 
Prof.  George  S.  Huntington,  of  the  College  of  Physi- 
cians and  Surgeons,  Colunibia  University,  for  the  aid 
and  many  valuable  suggestions  which  they  have  given 
me ;  as  well  as  acknowledge  my  indebtedness  to  my 
former  teacher.  Dr.  F.  Hochstetter,  assistant  at  the 
Vienna  University,  for  the  many  hours  which  we 
have  passed  together  in  the  study  of  this  subject.  I 
am  also  indebted  to  Toldt,  Hertwig,  Gegenbauer, 
Quain,  and  Gray,  for  sketches  taken  from  their 
works. 

Franklin  Dextee, 
Assistant  Demonstrator  of  Anatomy, 
College  of  Physicians  and  Surgeons, 

New  York. 


ANATOMY  OF  THE  PERITONAEUM. 


DEVELOPMENT  OF  THE  ALIMENTARY 
CANAL. 

Fig.  L 

Median  section  of  an  embryo.  In  a  very  young 
embryo  the  alimentary  canal  resembles  a  tube  in  its 
form. 


Fig.  II. 

At  a  later  date  a  slight  enlargement  occurs  in  it, 
which  is  the  first  indication  of  the  stomach,  and  infe- 
riorly  the  canal  makes  a  distinct  bend. 


Fig.  I. — A,  Aorta. 
Ac,  Alimentary  canal. 


Fig.  II.  —  S,  Rudimentary 
stomach.  A,  Aorta.  B, 
Bend  in  intestine. 


10  ANATOMY  OF  THE  PERITONAEUM. 


Fig.  III. 

The  enlargement  (stomach)  increases  in  size,  the 
bend  in  the  intestine  grows  more  pronounced,  and  the 
lowest  loop  of  the  bend  is  approximated  to  the  upper 
part  of  the  intestine. 


Fig.  in. — S,  Stomach.     A,  Aorta.     B,  Bend  in  intes- 
tine. 


12  ANATOMY  OF  THE  PERITONEUM. 


Fig.  IY. 

At  about  this  time  a  differentiation  in  the  size  of 
the  intestine  takes  j)]ace.  The  bend  in  the  large  has 
crossed  the  small  intestine,  and  just  below  the  stom- 
ach two  sprout-like  processes  are  given  off  from  the 
small  intestine,  one  anteriorly  and  one  posteriorly  to 
it.  These  are  the  first  indications  of  the  liver  and 
pancreas  respectively. 


Fig.  ly. — S,  Stomach.    A,  Aorta.    C,  Colon.    L,  Liver. 
P,  Pancreas. 


14  ANATOMY  OF  THE  PERITONEUM. 


Fig.  y. 

An  anterior  view  of  an  embryo  in  the  next  stage 
of  development  shows  us  that  tlie  large  intestine  has, 
so  to  speak,  fallen  over  the  small  intestine.  This 
happens  in  such  a  manner  that  the  large  intestine 
comes  to  lie  anteriorly  to  the  small,  crosses  it,  and 
indicates  in  a  general  way  the  direction  of  the  trans- 
verse and  descending  colon.  The  liver  and  pancreas 
have  not  here  been  drawn  in,  for  the  sake  of  sim- 
plicity. 


-— \— Tc 


Coe— 


■--De 


Fig.  V. — A,  Aorta.    S,  Stomach.    Tc,  Transverse  colon. 
Dc,  Descending  colon.     Coe,  caecum. 


10  ANATOMY  OF   THE  PERITONEUM. 


Fig.  YI. 

At  a  later  date  the  differentiation  in  the  size  of 
the  intestines  is  more  marked.  The  vermiform  ap- 
pendix is  not  of  uniform  size,  as  in  the  adult,  but  it 
seems  to  be,  as  it  really  is,  a  portion  of  the  caecum. 
That  there  is  no  ascending  colon  is  an  important 
point,  as  well  as  the  high  position  of  the  caecum. 
Later,  the  first  portion  of  the  large  intestine  grows 
downward,  until  the  caecum  reaches  its  normal  po- 
sition in  the  right  iliac  fossa.  In  this  way  the  as- 
cending colon  is  formed.  That  the  caecum  has  nor- 
mally this  high  position  in  the  embryo  is  important, 
for  I  have  seen  cases  in  the  dissecting  room  of  chil- 
dren whose  caeca  were  found  to  be  in  relation  to  the 
liver  rather  than  to  the  iliac  fossa.  This  abnormity 
can  easily  be  accounted  for  by  the  lack  of  develop- 
ment of  the  ascending  colon. 


Fig.  VI. — Coe,  Caecum.    Va,  Vermiform  appendix. 
A  Aorta. 


18  ANATOMY  OF  THE  PERITONEUM. 


Fig.  YII. 

The  stomach  has  now  more  its  adult  form — that  is 
to  say,  its  two  ends  have  approached  each  other,  and, 
moreover,  it  is  so  turned  tliat  what  was  formerly  its 
anterior  border  is  now  its  superior  or  lesser  curvature, 
and  what  was  its  posterior  border  is  now  its  inferior 
or  greater  curvature.  This  is  important,  as  we  shall 
see  later.  The  small  intestine  has  greatly  increased 
in  length,  and  the  caecum  has  reached  its  normal 
position,  in  the  right  iliac  fossa. 


Fig.  VII. — S,  Stomach.  Ac,  Ascending  colon.  Tc, 
Transverse  colon.  Dc,  Descending  colon.  Coe, 
caecum. 


20  ANATOMY   OF  THE  PERITONAEUM. 

MESENTEEY 

Fig.  YIII. 

The  blood-vessels  supplying  the  alimentary  tract 
need  some  support,  and  they  find  it  in  a  more  or  less 
loose  connective  tissue  which  binds  them  together. 
It  is  necessary  that  they  should  have  a  lubricated  sur- 
face, in  order  to  diminish  friction,  and  so  allow  the 
peristaltic  movement  of  the  intestines  to  be  carried  on 
as  smoothly  as  possible.  So  the  blood-vessels  in  their 
bed  of  connective  tissue  are  surrounded  by  a  shining 
membrane  called  the  peritonseum.  All  these  together 
— vessels,  tissue,  and  peritonaeum — constitute  what  is 
known  as  the  mesentery. 

Every  organ  has  its  mesentery,  under  that  name 
or  some  other.  For  instance,  the  name  mesentery  is 
usually  applied  to  the  mesentery  of  the  small  intes- 
tine ;  the  mesocaecum,  to  the  mesentery  of  the  cae- 
cum ;  the  transverse  mesocolon,  to  the  mesentery  of 
the  transverse  colon ;  and  the  mesorectum,  to  the 
mesentery  of  the  rectum.  Moreover,  other  organs 
have  their  mesenteries,  though  their  nature  is  not 
designated  by  their  name.  The  lesser  omentum  is 
the  mesentery  of  the  liver,  the  greater  omentum  the 
mesentery  of  the  stomach,  spleen,  and  pancreas.  It 
will  be  seen  from  this  that  mesenteries  vary  much  in 
thickness.  They  may  be  very  thin,  like  the  omenta, 
or  much  stronger,  as  in  the  ascending  mesocolon. 


Fig.  VIII. — Vp,  Visceral  peritonaeum.  Pp,  Parietal 
peritonaeum.  M,  Mesentery.  I,  Intestine.  T,  Con- 
nective tissue.     V,  Vessels. 


22  ANATOMY  OF  THE  PERITONEUM. 

Fig.  IX. 

Figs.  IX,  X,  and  XI  are  transverse  sections  of 
an  embryo  at  different  ages,  to  show  two  points: 
first,  that  the  peritonaeum  is  developed  simultaneous- 
ly with  the  intestine ;  second,  to  show  the  mode  of 
development  of  the  mesentery. 

Fig.  IX  is  the  youngest  embryo,  and  at  this  date 
the  intestine  is  not  closed  ;  nevertheless,  it  is  entirely 
covered  by  peritonaeum  (the  green  line),  which  is  re- 
flected on  to  the  sides  of  the  peritoneal  cavity.  This 
shows  us  that  there  are  two  forms  of  peritonaeum — 
one  usually  described  as  the  visceral,  because  it  sur- 
rounds a  viscus ;  the  other  as  the  parietal,  because  it 
lines  the  parietal  walls.  The  peritonaeum  of  the  me- 
sentery is  always  of  the  former  variety.  In  these 
drawings  the  parietal  peritonaeum  will  be  represented 
by  a  green  line ;  but  all  mesenteries — ^to  show  that  they 
are  such — by  a  black  line  between  two  green  ones. 
The  black  line  corresponds  to  the  connective-tissue 
support  of  the  vessels.  We  see,  then,  that  the  peri- 
tonaeum is  developed  simultaneously  with  the  intes- 
tine, and  that  the  intestine  has  not,  after  it  has  been 
formed,  been  pushed  into  the  membrane  as  a  finger  is 
into  a  glove.  This  explanation  or  comparison  of  the 
covering  of  the  intestine  by  peritoneum,  which  is  so 
often  given,  is  not  a  fortunate  one,  for  it  implies  at 
least  a  totally  wrong  principle. 


Fig.  IX. — Pp,  Parietal  peritonaeum.  .  Vp,  Visceral  peri- 
tonaeum.    I,  Intestine.     Pc,  Peritoneal  cavity. 


24  ANATOMY  OF   THE  PERITONEUM. 


Fig.  X. 

Fig.  X  represents  the  embryo  at  a  later  date. 
The  intestine  is  gradually  closing,  and  is  attached  to 
the  embryo  by  a  very  short  mesentery. 


Fig.  XL 

In  Fig.  XI  the  shape  of  the  embryo  is  somewhat 
changed.  The  intestine  is  closed,  and  the  mesentery 
has  very  much  increased  in  length.  It  increases  in 
length  by  growth,  which  might  be  likened  to  a  pro- 
cess of  stretching. 


Fig.  X. — M,  Mesentery. 


Fig.  XL — Pc,  Peritoneal  cavity.  Pp,  Parietal  perito- 
naeum. Vp,  Visceral  peritonaeum.  M,  Mesentery. 
I,  Intestine. 


26  ANATOMY  OF  THE  PERITONEUM. 


Fig.  XII. 

For  the  sake  of  simplicity,  when  considering  the 
development  of  the  alimentary  canal,  its  mesenteries 
were  omitted.  On  the  examination  of  a  very  young 
embryo  at  a  period  when  its  alimentary  canal  presents 
a  tube-like  appearance,  we  find  that  it  possesses  two 
mesenteries — a  posterior  mesentery,  attached  anteri- 
orly to  the  alimentary  canal  and  posteriorly  to  the 
aorta.  Its  vessels  (not  here  represented)  are  branches 
of  the  aorta.  It  has  also  an  anterior  mesentery,  at- 
tached posteriorly  to  the  canal  and  anteriorly  to  the 
median  line  of  the  abdominal  wall.  This  mesentery 
extends  only  as  far  downward  as  the  umbilicus.  The 
abdominal  cavity  is  lined  anteriorly  and  posteriorly, 
as  well  as  on  each  side,  by  the  parietal  peritonaeum, 
which  is  reflected  on  to  the  mesenteries,  and  thence 
on  to  the  gut,  constituting  the  visceral  layer  of  peri- 
tonaeum (Fig.  XX). 


Fig.  XII. — A,  Aorta.  Ac,  Alimentary  canal.  Pm,  Pos- 
terior mesentery.  Am,  Anterior  mesentery.  U,  Um- 
bilicus. 


28  ANATOMY  OF  THE  PERITONEUM. 


Fig.  XIII. 

The  relation  of  the  anterior  mesentery  is  un- 
changed by  the  development  of  the  bend  in  the  canal. 
The  posterior,  however,  presents  a  somewhat  different 
appearance.  This  mesentery  appears  to  be  shortened 
where  the  inferior  bend  occurs.  The  stomach  and  the 
first  part  of  the  small  intestine  have  an  anterior  as 
well  as  a  posterior  mesentery.  The  posterior  mesen- 
tery of  the  stomach  is  also  called  the  mesogastriumo 


Am 


u 


Fig.  XIIL— a,  Aorta.  S,  Stomach.  Pm,  Posterior 
mesentery  or  mesogastrium.  Am,  Anterior  mesen- 
tery,    lb,  Inferior  bend.     U,  Umbilicus. 


30  ANATOMY  OP  THE   PERITONEUM. 


Fig.  XIY. 
The  blood-vessels  have  been  represented  in  this 
plate  to  show  that  even  at  this  earlj  date  the  ves- 
sels supplying  the  organs  correspond  to  the  vessels 
in  the  adult  —  the  cocliac  axis,  to  supply  the  stom- 
ach, liver,  and  spleen ;  the  superior  mesenteric  ar- 
tery, to  supply  the  caecum,  ascending  and  transverse 
colon ;  the  inferior  mesenteric,  to  supply  the  de- 
scending colon,  sigmoid  flexure,  and  rectum. 


Fig.  XIV. — Oa,  Coeliac  axis.     Sm,  Superior  mesenteric 
artery.     Iin,  Inferior  mesenteric  artery. 


32  ANATOMY  OF  THE  PERITONEUM. 


Fig.  XY. 

The  posterior  mesentery  is  somewhat  changed  in 
appearance  by  the  crossing  of  the  intestine.  The 
loop  of  intestine,  with  its  mesentery,  seems  to  be 
separated  from  the  posterior  mesentery,  yet  it  is  not ; 
its  connecting  band  lies  between  the  two  parts  of  the 
crossing  intestine,  but  can  not  be  seen  in  this  plate. 
The  liver  develops  from  the  intestine  and  lies  in  the 
anterior  mesentery.  The  pancreas  likewise  originates 
from  the  intestine,  but  lies  in  the  posterior  mesentery 
or  mesogastrium. 


Fig.  XV. — Lo,  Lesser  omentum.  S,  Stomach.  M,  Meso- 
gastrium.  P,  Pancreas.  D,  Diaphragm.  L,  Liver. 
Am,  Anterior  mesentery.     U,  Umbilicus. 


34  ANATOMY  OP  THE  PERITONEUM. 

Fig.  XYI. 

Fig.  XYI  is  an  anterior  view  of  the  embryo,  rep- 
resenting the  alimentary  canal  after  the  large  has 
fallen  over  the  small  intestine.  In  this  plate  the  an- 
terior mesentery  has  been  entirely  omitted,  and  all 
the  mesentery  here  seen  is  posterior  mesentery.  The 
mesogastrium  is  attached  to  the  median  line  ;  it  then 
disappears  behind  the  stomach ;  it  is  again  seen  ap- 
pearing from  behind  the  stomach,  to  be  attached  to 
its  greater  curvature. 

It  must  be  borne  in  mind  that  the  stomach  has 
now  materially  altered  its  position.  Its  two  ends 
have  approximated  each  other.  It  has  so  turned  that 
what  was  formerly  its  anterior  border  is  now  its  lesser 
curvature,  and  what  was  its  posterior  border  is  now 
its  greater  curvature.  We  saw  that  the  posterior 
mesentery  was  attached  to  the  posterior  border  of  the 
stomach  and  to  the  aorta.  lN"ow,  as  the  greater  curva- 
ture corresponds  to  what  was  the  posterior  border  of 
the  organ,  and  as  the  mesogastrium  has  not  changed 
its  place  of  attachment,  we  find  it  attached  to  the 
greater  curvature  of  the  stomach.  Moreover,  what 
was  formerly  the  left  surface  of  the  stomach  has  now 
become  its  anterior  surface,  and  its  right  has  become 
its  posterior  surface.  This  would  explain  the  distri- 
bution of  the  left  pneumogastric  nerve  to  the  ante- 
rior and  the  right  to  the  posterior  surface  of  the 
stomach. 


Fig.  XVI. — A,  Aorta.  S,  Stomach.  M,  Mesogastrmm. 
Mc,  Mesentery  of  colon.  Mi,  Mesentery  of  intes- 
tine.    Ms,  Mesentery  of  sigmoid  flexure. 


36  ANATOMY  OF  THE  PERITONAEUM. 


Fig.  XYII. 
If  it  is  not  easily  understood  how  a  portion  of  the 
duodenum  is  hidden  from  view  by  the  mesentery  of 
the  transverse  colon,  any  one  can  demonstrate  it  for 
himself  by  the  construction  of  a  very  simple  mod- 
el. Take  a  board  and  fasten  to  it  an  India-rubber 
tube,  bent  in  such  a  way  as  to  resemble  the  bend  in 
the  embryo  intestine.  A  thin  sheet  of  India-rubber 
(such  as  dentists  use  for  their  rubber  dam)  makes  a 
very  good  posterior  mesentery.  This  should  be  sewed 
to  the  tube  and  attached  to  the  surface  of  the  board. 
N^ow  we  have  a  side  view  of  the  embryonic  aliment- 
ary canal  with  its  posterior  mesentery. 


Fig.  XVII.— B,  Board.     T,  Tube.     R,  Eubber  sheet. 


38  ANATOMY  OF  THE  PERITONEUM. 


Fig.  XYIII. 

The  ascending  portion  of  the  bend  should  be  ap- 
proximated to  the  descending  until  the  loop  falls  over, 
and  it  will  be  seen  that  a  part  of  the  tube  is  covered 
by  the  rubber  sheet  (the  edge  of  the  board  corre- 
sponding to  the  front  of  the  embryo  should  now  be 
turned  toward  the  observer).  This  sheet  represents 
the  mesentery  of  the  transverse  colon,  the  covered 
rubber  tube  the  so-called  third  portion  of  the  duo- 
denum, and,  in  the  model,  now  to  see  it  one  must 
tear  through  the  rubber  sheet.  Thus  it  is  explained 
how  in  the  adult  the  jejunum  seems  suddenly  to 
appear  in  the  abdomen,  and  the  third  portion  of  the 
duodenum  is  invisible.  This  portion  of  the  duol 
denum  is  covered  by  the  mesentery  of  the  transverse 
colon,  and  if  this  is  cut  through  the  duodenum  wil- 
come  to  light  in  the  same  way  the  tube  did  when  the 
rubber  sheet  was  torn. 


Fig.  XYIII. 


40  ANATOMY  OF  THE  PERITONEUM. 


Fig.  XIX. 

Fig.  XIX  is  the  same  as  Fig.  XYI,  only  at  a  later 
date.  The  mesogastrium  is  seen  to  be  more  devel- 
oped, so  that  it  forms  quite  a  little  sac  behind  and  to 
the  left  as  well  as  below  the  stomach.  After  it  has 
reached  this  period  of  growth  it  is  spoken  of  eitlier 
as  the  posterior  mesentery  of  the  stomach,  the  meso- 
gastrium, or  the  great  omentum,  the  names  being 
applied  to  one  aiid  the  same  thing.  The  interior  of 
the  sac — i.  e.,  the  space  between  the  mesogastrium 
and  the  stomach — is  known  as  the  lesser  cavity  of  the 
peritonaeum,  or  the  cavity  of  the  great  omentum. 


Fig.  XIX. — X,  Line  of  section  of  Fig.  XX.    M,  Meso- 
gastrium. 


42  ANATOMY  OF  THE  PERITONEUM. 


MESENTERY   OF  THE  INTESTINE  IN 
EMBRYO. 

Fig.  XX. 

Suppose  a  transverse  section  of  Fig.  XIX  be 
made  just  below  the  transverse  colon.  We  should 
see  the  mesentery  of  the  small  intestine,  as  well  as 
the  mesentery  of  the  ascending  and  descending  colon, 
all  attached  posteriorly  to  the  aorta ;  the  abdominal 
cavity  lined  by  the  parietal  peritonaeum  ;  the  kidneys 
lying  external  to  it,  in  what  is  known  as  the  retro- 
peritoneal space  (consequently  they  are  covered  only 
on  their  anterior  surfaces  by  peritonaeum).  The  im- 
portant point  is  that  both  the  large  and  small  intes- 
tines have  a  long  and  freely  movable  mesentery,  and 
are  in  no  way  fixed  in  the  abdomen,  except  where 
their  mesenteries  are  attached  to  the  aorta.  This  is 
the  actual  condition  of  the  intestines  in  the  foetus, 
and  often  even  at  birth. 


Pp-- 


FiG.  XX. — Si,  Small  intestine.  M,  Mesentery.  C,  Colon. 
Mc,  Ascending  mesocolon.  K,  Kidney.  A,  Aorta. 
Rs,  Retroperitoneal  space.   Pp,  Parietal  peritonaeum. 


44  ANATOMY  OF  THE  PERITONEUM. 


Fig.  XXI. 

In  the  adult,  however,  it  is  different.  The  small 
intestine  remains  unchanged,  but  tlie  ascending  and 
descending  colon  become  adherent  to  the  posterior 
abdominal  wall.  That  is  to  say,  the  parietal  peri- 
tonaeum, as  well  as  the  peritonaeum  on  the  posterior 
surface  of  their  mesenteries  and  a  portion  of  the  peri- 
tonaeum on  the  colon  itself,  becomes  changed  to  con- 
nective tissue  (represented  in  the  plate  in  brown). 
By  means  of  this  connective  tissue  the  ascending  and 
descending  colon,  at  or  soon  after  birth,  become  im- 
movably fixed  to  the  posterior  abdominal  wall.  It 
explains,  moreover,  how  it  comes  about  that  they  are 
only  partially  covered  by  peritonaeum,  and  how  it  is 
possible  in  the  adult,  but  not  in  a  very  young  child, 
to  enter  the  ascending  or  descending  colon  posterior- 
ly without  injury  to  the  peritonaeum.  In  this  opera- 
tion the  operator  would  pass  through  the  connective 
tissue,  and  the  peritoneal  covering  of  the  gut  would 
remain  uninjured.  It  is  interesting  to  note  (speaking 
generally)  that  the  intestines  of  the  higher  animals  as 
regards  this  point  resemble  the  condition  found  in  the 
foetus. 


Sf-~^. 


Fig.  XXI. — C,  Colon.  K,  Kidney.  Mc,  Ascending 
mesocolon.  T,  Connective  tissue.  Pp,  parietal 
peritonaeum.     Si,  Small  intestine. 


46  ANATOMY  OF  THE  PERITONEUM. 


Fig.  XXII. 

In  the  adult,  as  was  just  explained,  the  mesentery 
of  the  descending  colon  becomes  attached  to  the  pos- 
terior abdominal  wall.  The  mesentery  of  the  sigmoid 
flexure,  however,  is  usually  only  attached,  as  in  the 
embryo,  to  the  median  line,  and  does  not  unite  with 
the  peritonaeum  of  the  posterior  abdominal  wall.  It 
is  long,  and  consequently  very  movable — so  much  so 
in  fact  that  the  ancients  described  the  normal  position 
of  sigmoid  flexure  to  be  on  the  right  side  of  the  body. 
An  unattached  sigmoid  flexure  is  the  rule,  but  to  find 
it  more  or  less  united  is  not  uncommon. 

Fig.  XXII  represents  the  descending  colon  and 
sigmoid  flexure  with  their  mesenteries.  The  dotted 
line  shows  the  limit,  inferiorly,  to  which  the  mesen- 
tery of  the  descending  colon  is  attached  to  the  poste- 
rior abdominal  wall.  As  the  sigmoid  flexure  is  not 
usually  attached  here,  but  is  quite  movable,  one  is  able 
to  lift  it  up,  and  will  find  on  so  doing  a  more  or  less 
triangular  cavity  or  fossa  beneath  it.  This  fossa  is 
bounded  in  the  median  line  by  the  attached  mesentery 
of  the  sigmoid  flexure,  and  above  by  the  dotted  line 
representing  the  limit  of  the  attachment  of  the  mesen- 
tery of  the  descending  colon.  It  is  called  the  sub- 
sigmoid  fossa.  Its  size  depends  upon  the  extent  of  at- 
tachment of  the  mesentery  of  the  sigmoid  flexure  to  the 
posterior  abdominal  wall.  If  this  line  of  attachment 
extends  lower  down  than  normal,  so  as  to  include  a 
part  of  the  sigmoid  flexure,  the  fossa  will  be  poorly 
developed ;  if,  on  the  other  hand,  the  entire  mesentery 
of  the  sigmoid  flexure  is  free,  the  fossa  will  be  large. 


Fig.  XXII. — A,  Aorta.  Dc,  Descending  colon.  Mc, 
Descending  mesocolon.  Sm,  Sigmoid  mesocolon. 
Sf,  Sigmoid  flexure. 


48  ANATOMY  OF  THE  PERITONEUM. 


MESENTERIES   OF   THE   LIVER  AND 
STOMACH. 

Fig.  XXIII. 

In  a  median  section  of  a  young  embryo  the  liver 
is  seen  developing  in  the  anterior  mesentery  of  the 
stomach  and  duodenum.  It  divides  this  mesentery 
into  what  is  called  the  anterior  mesentery  of  the  liver 
and  the  anterior  mesentery  of  the  stomach  or  lesser 
omentum.  From  the  first  moment  the  liver  is  dis- 
tinguishable it  is  connected  not  only  to  the  intestine, 
but  also  to  the  diaphragm.  It  is,  in  fact,  a  part  of 
the  latter,  and  it  is  of  the  utmost  importance  to 
always  think  of  it  as  an  appendage  to  the  diaphragm, 
and  at  no  period  of  life  separate  from  it.  The  pan- 
creas is  seen  developing  in  the  mesogastrium. 


Am- 


FiG.  XXIII. — Lo,  Lesser  omentum.  S,  Stomach.  M» 
Mesogastrium.  P,  Pancreas.  D,  Diaphragm.  L, 
Liver.     Am,  Anterior  mesentery.     U,  Umbilicus. 


50  ANATOMY  OF  THE  PERITONEUM. 


Fig.  XXIV. 

A  transverse  section  through  the  stomach  of  the 
same  embryo  would  present  this  picture:  The  peri- 
toneal cavity  lined  by  its  parietal  peritonaeum  ;  the 
stomach  connected  with  the  posterior  abdominal  wall 
by  its  mesogastrium  or  greater  omentum ;  with  the 
liver  by  its  anterior  mesentery  or  lesser  omentum  ; 
and,  lastly,  the  liver  connected  with  the  anterior  ab- 
dominal wall  by  its  anterior  mesentery. 


Am 


Fig.  XXIV. — Am,  Anterior  mesentery  of  liver.  L, 
Liver.  S,  Stomach.  Lo,  Lesser  omentum.  Pp, 
Parietal  peritonaeum.     M,  Mesogastrium. 


52  ANATOMY  OF  THE  PERITONEUM. 


Fig.  XXY. 

This  sketch  differs  from  the  last  in  that  the  em- 
bryo is  older,  and  consequently  the  organs  are  more 
developed.  The  stomach  and  liver  present  much  the 
same  appearance  as  in  the  last  drawing,  but  the  pan- 
creas has  been  included  in  this  plate.  The  mesogas- 
trium  is  longer — it  seems  curved — and,  what  is  very 
important,  is  the  appearance  of  the  spleen.  This 
organ  is  not  only  developed  in,  but  also  from,  the 
mesogastrium. 


fMTK^ 

"/^\    ^^7^^ 

D 

1             '^^^^,^1) 

'pi ->S 

M' 


Pig.  XXV.— L,  Liver.  S,  Stomach.  Sp,  Spleen.  P, 
Pancreas.  Am,  Anterior  mesentery.  Lo,  Lesser 
omentum.     M,  Posterior  mesentery. 


54  ANATOMY  OF  THE  PERITONEUM. 


Fig.  XXYI. 
A  sagittal  section  of  an  embryo  about  the  same 
age  as  in  the  last  sketch  would  present  this  appear- 
ance: In  Fig.  XXY  the  great  omentum  was  devel- 
oping laterally,  and  now  it  is  seen  also  to  have  grown 
downward  as  well,  so  as  to  form  a  distinct  sac.  The 
pancreas  has  been  met  in  the  section,  and  is  contained 
within  the  mesogastrium. 


Fig.  XXVI.— L,  Liver.  P,  Pancreas.  Pp,  Parietal 
peritonaeum.  Go,  G-reat  omentum  or  mesogastrium. 
S,  Stomach.  Lo,  Lesser  omentum.  D,  Diaphragm. 
Co,  Cavity  of  greater  omentum. 


56  ANATOMY  OF   THE  PERITONEUM. 


Fig.  XXYII. 

A  very  diagrammatic  view  of  only  the  greater 
omentum  and  the  stomach,  seen  from  before,  may 
make  the  last  two  drawings  plainer.  It  must  always 
be  borne  in  mind  that  the  change  in  the  position  of 
the  stomach  (as  described  on  page  34)  has  materially 
altered  the  direction  of  the  omenta.  They  both  pass 
much  more  in  a  transverse,  inferior  direction  than 
they  formerly  did.  Moreover,  the  great  omentum, 
although  still  attached  ^posteriorly  to  the  median  line, 
has  developed  very  much  to  the  left,  as  well  as  in- 
feriorly.  It  does  not,  in  other  words,  make  a  straight 
line  between  the  aorta  and  greater  curvature  of  the 
stomach,  but  passes  to  the  left  of  the  stomach,  de- 
scends, and  then  ascends  once  more  to  attach  itself  to 
the  greater  curvature,  and  in  this  way  forms  the  sac, 
as  before  mentioned,  which  is  the  cavity  of  the  great 
omentum  or  lesser  cavity  of  the  peritonaeum. 


— M 


Fig.  XXVII. — S,  Stomach.     M,  Posterior  mesentery, 
mesogastrium,  or  great  omentum. 


58  ANATOMY  OP  THE  PERITONEUM. 


Fig.  XXYIII. 
Owing  to  the  mentioned  change  in  the  position  of 
the  stomach,  as  well  as  to  a  further  development  in 
the  shape  of  the  organs,  this  section  differs  materially 
from  the  last.  The  section  has  passed  between  the 
liver  and  stomach,  dividing  the  lesser  omentmn. 
This  seems  to  be  attached  to  the  greater  curvature  or 
to  the  posterior  surface  of  the  stomach,  but  this  is  not 
the  case.  It  is  still  attached  to  the  lesser  curvature, 
the  erroneous  impression  being  due  to  the  change  in 
the  position  of  the  stomach,  and  consequently  a 
change  in  the  direction  of  the  lesser  omentum.  The 
spleen  is  seen  as  before,  but  more  developed,  and  the 
lateral  inclination  of  the  great  omentum  is  marked. 
The  pancreas  is  still  surrounded  by  the  peritonaeum, 
derived  from  the  great  omentum,  but  it  is  now  rest- 
ing upon  the  parietal  peritonaBum.  This  picture 
would  correspond  to  the  condition  of  the  pancreas 
just  before  birth,  or,  at  times,  in  a  very  young  child 
— enveloped  by  the  peritonaeum  of  its  mesentery, 
and  resting  upon  the  posterior  parietal  peritonaeum. 
The  position  of  the  kidneys  is  unchanged.  They  lie 
in  the  retroperitoneal  space. 


^Lo 


Fig.  XXVIII.— E,  Round  ligament  of  the  liver.  S, 
Stomach.  Lo,  Lesser  omentum  with  vessels  going 
to  the  liver.  K,  Kidney.  P,  Pancreas.  Sp,  Spleen. 
Go,  Great  omentum. 


60  ANATOMY  OF  THE  PERITONAEUM. 

Fig.  XXIX. 

The  change  at  this  stage  is  marked,  and  corre- 
sponds to  what  is  generally  found  at  birth.  The 
layer  of  parietal  peritonaeum  posterior  to  the  pan- 
creas, as  well  as  the  visceral  layer  on  its  posterior 
surface,  derived  from  the  mesogastrium,  have  been 
changed  to  connective  tissue.  The  pancreas  has  con- 
sequently entirely  lost  its  posterior  peritoneal  cover- 
ing. The  spleen  and  stomach  are  more  developed, 
and  the  great  omentum  extends  still  farther  to  the 
left.  It  has  now  increased  laterally  to  such  an  extent 
that  it  forms  quite  an  extensive  sac  behind  the  stom- 
ach, which,  as  was  before  mentioned,  is  known  as  the 
lesser  cavity  of  the  peritonaeum.  Between  the  vessels 
going  to  the  liver  and  the  aorta  this  lesser  cavity  con- 
nects with  the  greater  peritoneal  cavity,  or,  in  other 
words,  with  the  rest  of  the  abdominal  cavity.  The 
connection  is  made  through  a  restricted  opening 
bounded  anteriorly  by  the  vessels  going  to  the  liver 
in  the  lesser  omentum  and  posteriorly  by  the  aorta 
(or,  more  accurately,  by  the  vena  cava,  which  is  not 
drawn  in).     This  opening  is  the  foramen  of  Winslow. 


Sp- 


FiG.  XXIX. — R,  Round  ligament  of  the  liver.  Lo,  Less- 
er omentum.  Fw,  Foramen  of  Winslow.  K,  Kid- 
ney. T,  Connective  tissue.  P,  Pancreas.  Sp, 
Spleen.     Go,  Great  omentum. 


62  ANATOMY  OF  THE  PERITONEUM. 


Fig.  XXX. 

A  sagittal  section  of  a  child  at  or  just  before  birth 
would  present  this  appearance :  The  liver  united  to 
the  diaphragm  and  covered  by  the  parietal  perito- 
naeum, reflected  from  the  diaphragm  as  well  as  by 
the  visceral  peritonaeum  reflected  from  the  lesser 
omentum;  the  lesser  omentum  between  liver  and 
stomach ;  the  stomach  covered  by  peritonaeum  de- 
rived from  its  mesenteries  (the  greater  and  lesser 
omentum) ;  the  great  omentum  extending  downward 
from  the  greater  curvature  of  the  stomach  and  form- 
ing the  downward  projection  of  the  lesser  cavity 
of  the  peritonaeum ;  the  pancreas  lying  behind  the 
peritonaeum  (the  parietal  peritonaeum  posterior  to  it 
as  well  as  its  posterior  visceral  layer,  derived  from 
the  great  omentum,  is  seen  to  have  changed  to  con- 
nective tissue).  The  pancreas  is  now  only  covered  on 
its  anterior  and  inferior  surfaces  by  peritonaeum,  both 
derived  from  the  great  omentum.  The  transverse 
colon  is  here  drawn  in  with  its  mesentery. 


Fig.  XXX.— L,  Liver.  Lo,  Lesser  omentum.  T,  Con- 
nective tissue.  P,  Pancreas.  0,  Colon.  D,  Dia- 
phragm. S,  Stomach.  Go,  Great  omentum.  Co, 
Cavity  of  great  omentum. 


64  ANATOMY  OF  THE  PERITONEUM. 


Fig.  XXXI. 
At  or  soon  after  birth  the  picture  is  somewhat 
modified.  The  posterior  layer  of  the  great  omentum 
has  become  adherent  to  the  transverse  colon  and  its 
mesentery,  so  that,  were  the  greater  omentum  lifted 
up,  the  colon  would  be  raised  with  it.  By  the  union 
of  the  great  omentum  with  the  transverse  mesocolon 
the  inferior  surface  of  the  pancreas  becomes  covered 
by  the  latter,  its  former  peritoneal  covering,  derived 
from  the  great  omentum,  having  been  changed  to 
connective  tissue.  So  it  is  now  covered  anteriorly  by 
the  great  omentum,  and  inferiorly  by  the  transverse 
mesocolon. 


Go- 


Fig.  XXXI. — Lo,  Lesser  omentum.  P,  Pancreas.  T, 
Connective  tissue.  C,  Colon.  Tm,  Transverse 
mesocolon.  Go,  Great  omentum.  L,  Liver.  D, 
Diaphragm. 


ee  ANATOMY  OF  THE  PERITONEUM. 


Fig.  XXXII. 

A  transverse  section  of  the  abdomen  of  an  adult 
which  passes  through  tlie  stomach  shows  a  further  ex- 
tension of  the  great  omentum  to  the  left  and  a  greater 
production  of  connective  tissue  behind  it  where  it  be- 
comes adherent  to  the  abdominal  wall.  This  connect- 
ive tissue  covers  the  left  kidney,  and  in  the  adult  can 
usually  be  demonstrated  on  the  left  side  as  a  distinct 
layer,  which  is  entirely  absent  on  the  right. 


.-Lo 


Fig.  XXXII. — S,  Stomach.  Sp,  Spleen.  P,  Pancreas. 
Lo,  Lesser  omentum.  Go,  Great  omentum.  T, 
Connective  tissue.  Fw,  Foramen  of  Winslow.  R, 
Round  ligament  of  liver. 


68  ANATOMY  OF  THE  PERITONEUM. 


DUODENUM. 


Fig.  XXXIII. 


Fig.  XXXIII  is  a  transverse  section  of  the  duo- 
denum in  embryo.  At  this  period  the  entire  duo- 
denum has  a  posterior  mesentery,  and  is  covered  by 
peritonseum.  The  first  portion  has  also  an  anterior 
mesentery.  In  the  adult  this  portion  is  entirely 
covered  by  peritonaeum  derived  from  its  mesenteries. 
The  anterior  mesentery  is  a  part  of  the  lesser  omen- 
tum, and  is  often  called  the  hepatico-duodenal  Hga- 
ment. 


Fig.  XXXIII. — Du,  Duodenum  in  embryo.     Pm,  Pos- 
terior mesentery. 


70  ANATOMY  OP  THE  PERITONEUM. 


Fia.  XXXIY. 

Fig.  XXXIY  represents  a  transverse  section  of 
the  second  portion  of  the  duodenum  after  birth.  The 
parietal  peritonaeum  behind  the  second  portion  (some 
little  time  before  birth),  as  well  as  the  posterior  peri- 
tonseum  of  its  mesentery,  are  changed  to  connective 
tissue,  so  that  at  an  early  date  the  second  portion  of 
the  duodenum  is  only  partially  covered  by  the  peri- 
tonseum. 


Fig.  XXXIV. — Du,  Second  portion  of  adult  duodenum. 
T,  Connective  tissue. 


72  ANATOMY  OF  THE  PERITONEUM. 


Fig.  XXXY. 

To  understand  the  third  portion  we  shall  have  to 
return  to  a  joung  embryo,  and  to  that  period  of  de- 
velopment when  not  only  the  transverse  colon  is  un- 
united with  the  posterior  layer  of  the  great  omentum, 
but  when  the  pancreas  is  in  the  great  omentum.  At 
this  date,  as  was  before  mentioned,  the  duodenum  has 
its  posterior  mesentery. 


Fig.  XXXV.— L,  Liver.    P,  Pancreas.    Du,  Duodenum. 

C,  Colon.     Go,  Great  omentum.     S,  Stomach.     D, 
Diaphragm. 


74  ANATOMY  OF  THE  PERITONEUM. 


Fig.  XXXYl. 

This  plate  is  the  same  as  Fig.  XXX,  except  that 
the  duodenum  is  represented.  It  still  has  its  mesen- 
tery. The  transverse  colon  has  not  yet  united  with  the 
posterior  layer  of  the  great  omentum,  so  the  pancreas 
is  covered  anteriorly  as  well  as  inferiorly  by  the  peri- 
tonaeum of  the  great  omentum. 


Fig.  XXXVI. — L,  Liver.  T,  Connective  tissue.  Du, 
Duodenum.  C,  Colon.  Go,  Great  omentum.  S, 
Stomach.     Lo,  Lesser  omentum.     P,  Pancreas. 


76  ANATOMY  OF  THE  PERITONEUM. 


Fig.  XXXYII. 

At  a  still  later  date — not  only  after  the  ascending 
and  descending  colons  have  become  adherent  to  the 
posterior  abdominal  wall,  but  also  after  the  transverse 
colon  and  mesocolon  have  united  with  the  great 
omentum — the  parietal  peritonaeum  posterior  to  the 
third  portion  of  the  duodenum  is  changed  to  con- 
nective tissue,  as  well  as  the  visceral  layer  on  its  pos- 
terior surface.  [It  must  always  be  borne  in  mind 
that,  by  means  of  the  turn  in  the  intestine,  that  this 
portion  of  the  duodenum  lies  posterior  to  the  trans- 
verse mesocolon.]  Its  anterior  and  superior  visceral 
layers  unite  with  the  transverse  mesocolon,  and  are 
changed  to  connective  tissue. 

In  this  way  the  third  portion  of  the  duodenum 
loses  its  peritoneal  covering  and  comes  to  lie  behind 
the  peritonaeum  in  the  retro-peritoneal  space,  as  well 
as  posterior  to,  and  covered  anteriorly  by,  the  trans- 
verse mesocolon. 


Fig.  XXXVII.— 01,  Coronary  ligament.  Du,  Duode- 
num. Tm,  Transverse  mesocolon.  Si,  Small  in- 
testine. 0,  Colon.  P,  Pancreas.  T,  Connective 
tissue.     Go,  Great  omentum. 


78  ANATOMY  OF  THE  PERITONEUM. 


STOMACH. 

In  the  embryo  this  organ  possesses  an  anterior  and 
a  posterior  mesentery.  The  anterior  is  attached  to 
the  median  hne  of  the  abdominal  wall  and  to  the  an- 
terior border  of  the  stomach ;  the  posterior  mesen- 
tery to  the  aorta  and  to  the  posterior  border  of  the 
stomach  (Fig.  XIII).  Later,  through  the  change  in 
the  position  of  the  organ,  the  anterior  mesentery,  or 
gastro-hepatic  ligament,  is  attached  to  the  lesser  curv- 
ature; the  posterior  mesentery,  or  mesogastrium,  to 
the  greater  curvature.  These  two  mesenteries  are 
also  called  the  lesser  and  greater  omentum,  respect- 
ively. The  former  is  the  mesentery  of  the  liver,  the 
latter  the  mesentery  of  the  spleen,  pancreas,  and 
stomach  (Figs,  XXIY  and  XXYI).  At  a  still  later 
date  the  great  omentum  ceases  to  pass  in  a  direct 
line  from  its  aortal  attachment  to  the  greater  curva- 
ture, but  makes  a  bend  to  the  left  and  extends  down- 
ward below  the  stomach,  returning  to  be  attached  to 
the  greater  curvature. 

Thus  the  great  omentum  forms  a  sac  which  ex- 
tends posteriorly,  to  the  left,  and  below  the  stomach 
(Fig.  XXYIII).  This  sac  is  known  as  the  lesser 
cavity  of  the  great  omentum,  and  communicates  with 
the  greater  peritoneal  cavity  by  means  of  the  foramen 
of  Winslow.     This  foramen  is  situated  inferior  to  the 


SPLEEN.  79 

caudate  lobe  of  the  liver,  posterior  to  the  lesser  omen- 
tum, and  anterior  to  the  vena  cava  (Fig.  XXIX).  It 
might  be  mentioned  that  more  or  less  fat  is  developed 
in  the  descending  and  ascending  layers  of  the  great 
omentum,  which  forms  a  protection  to  the  intestines. 
After  the  adhesion  of  the  transverse  colon  to  the 
great  omentum  a  further  adhesion  of  its  two  leaves 
takes  place,  and  so  obliterates  the  cavity  of  the  great 
omentum  inferior  to  the  transverse  colon.  The  stom- 
ach at  all  periods  of  life  is  covered  by  reflections  of 
visceral  peritonaeum  derived  from  its  mesenteries. 

It  might  be  well  here  to  repeat  that  the  posterior 
mesentery  of  the  stomach  is  a  synonym  for  mesogas- 
trium,  and  that  after  it  has  developed  suflficiently  to 
form  a  sac  it  is  called  the  great  omentum.  The  an- 
terior mesentery  of  the  stomach,  gastro-hepatic  liga- 
ment, and  lesser  omentum,  are  also  synonyms. 

SPLEEIS". 

The  spleen  is  developed  from  as  well  as  in  the 
mesogastrium.  It  is  at  all  times  entirely  surrounded 
by  the  visceral  peritonaeum  derived  from  its  mesen- 
tery (Figs.  XXY,  XXYIII,  and  XXXII).  That  por- 
tion of  the  great  omentum  between  the  spleen  and 
stomach  is  often  referred  to  as  the  gastro-splenic  liga- 
ment. 


80  ANATOMY  OF  THE  PERITONEUM. 


PANCREAS. 

This  organ  originates  from  the  intestine,  and  is 
developed  in  the  mesogastrium  (Figs.  XV,  XXYII, 
and  XXXY). 

In  the  embryo  it  is  surrounded  by  peritonaeum 
derived  from  its  mesentery.  Later  the  parietal  peri- 
tonaeum posterior  to  it,  as  well  as  its  posterior  visceral 
layer,  become  changed  to  connective  tissue,  and  in 
this  way  it  entirely  loses  its  posterior  peritoneal 
covering  (Fig.  XXIX).  After  the  union  of  the  trans- 
verse colon  and  its  mesentery  with  the  posterior 
layer  of  the  great  omentum,  the  visceral  layer,  cover- 
ing the  inferior  surface  of  the  pancreas,  is  changed  to 
connective  tissue  ;  so  that  in  an  adult  we  find  the 
pancreas  covered  anteriorly  by  the  peritonaeum  of  the 
great  omentum,  inferiorly  by  the  transverse  meso- 
colon, and  lying  in  the  retroperitoneal  space  (Figs. 
XXXII  and  XXXI). 


LIVER. 

The  liver  originates  in  a  sprout-like  process  from 
the  intestine,  it  is  developed  in  the  anterior  mesen- 
tery, and  at  all  periods  of  life  is  inseparable  from  the 
diaphragm.  It  should  be  considered,  as  it  really  is,  a 
part  of  it.     If  we  think  of  the  liver  in  this  way,  as 


LIVER.  81 

a  portion  of  the  diaphragm,  not  only  in  the  embryo, 
but  also  in  the  adult,  our  difticulties  in  understanding 
the  so-called  ligaments  of  the  liver  will  be  materially 
diminished  (Fig.  XY).  The  inferior  surface  of  the 
diaphragm  is  covered  by  parietal  peritonaeum,  which 
is  reflected  over  the  liver,  and  these  reflections  form 
some  of  its  ligaments.  The  gall-bladder  is  developed 
by  a  sprouting  process  from  the  gall-duct,  and  is  a 
part  of  the  liver,  just  as  the  liver  is  a  part  of  the  dia- 
phragm. The  liver  is  consequently  entirely  covered 
by  peritonseum,  which  is  derived  from  the  parietal 
peritonaeum  on  the  inferior  surface  of  the  diaphragm, 
as  well  as  from  reflections  of  visceral  peritonaeum  de- 
rived from  its  mesenteries  (Fig.  XXXYII).  Should 
we  dissect  the  gall-bladder  from  the  liver,  or  the  liver 
from  the  diaphragm,  on  their  attached  surfaces  there 
would  be  no  peritoneal  covering,  any  more  than  there 
would  be  if  we  made  a  section  through  the  liver  and 
expected  to  find  peritonaeum  on  its  cut  surface. 


ANATOMY  OF  THE  PERITONEUM. 


Fig.  XXXYIII. 

This  figure  represents  the  so-called  posterior  sur- 
face of  the  liver  after  it  has  been  artificially  separated 
from  the  diaphragm.  (The  posterior  surface  is  con- 
vex, but  here  has  been  represented  as  flat,  for  the 
sake  of  clearness.)  Around  its  diaphragmatic  or 
posterior  surface  are  seen  the  cut  edges  of  some  of 
the  ligaments,  which,  to  repeat,  are  mostly  reflections 
of  peritonaeum  from  the  diaphragm.  Two  of  these 
layers  are  described  as  the  coronary  ligaments,  and 
are  attached  to  the  superior  and  inferior  borders  of 
this  surface.  They  end  in  more  or  less  pointed 
processes,  one  on  each  lobe,  to  which  the  name  lat- 
eral ligament  has  been  given,  though  they  are  simply 
continuations  of  the  coronary.  Moreover,  the  ante- 
rior mesentery  can  be  seen,  and  it  is  the  remains  of 
this  mesentery  which  forms  the  suspensory  ligament. 
It  extends  from  the  diaphragm  to  the  superior  sur- 
face of  the  liver,  and  from  the  anterior  abdominal 
wall  to  its  anterior  border.  The  umbilical  vein 
limits  the  anterior  mesentery  inferiorly.  In  fact,  it 
is  contained  in  its  folds,  surrounded  by  it,  but  not 
completely,  for  on  its  anterior  surface  it  is  destitute 
of  peritoneal  covering  (Fig.  XXYIII).  This  vein  in 
the  embryo  enters  the  umbilical  fissure  on  the  inferior 
surface  of  the  liver,  and  is  continued  by  means  of  the 
ductus  venosus  to  the  vena  cava,  which  is  situated  on 
its  so-called  posterior  surface.  After  birth  these 
veins  are  obliterated,  and  constitute  the  remains  of 
the  ductus  venosus  and  the  round  ligament  of  the 
liver.  In  the  drawing,  between  the  ductus  venosus 
and  vena  cava,  the  Spigelian  lobe  is  seen,  which  is,  of 
course,  covered  by  peritonaeum,  as  it  is  a  part  of  the 
free  surface  of  the  organ. 


Fig.  XXXVIII. — Vc,  Yena  cava.  Sc,  Superior  coronary 
ligaments.  Ic,  Inferior  coronary  ligaments.  S, 
Spigelian  lobe.  All,  Right  lateral  ligament.  Lll, 
Left  lateral  ligament.  SI,  Suspensory  ligament 
(anterior  mesentery).  Dv,  Ductus  venosus.  X, 
Diaphragmatic  or  posterior  surface  of  liver  which 
is  uncovered  by  peritonaeum. 


84:  ANATOMY  OF  THE  PERITONEUM. 

JEJUNUM  AND   ILIUM. 

These  portions  of  the  small  intestine  have  a  me- 
sentery, are  freely  movable,  and  are  at  all  periods  of 
life  covered  by  peritonaeum  (Fig.  XXI). 

C^CUM. 

The  relation  of  the  peritonaeum  to  the  caecum  is 
very  variable.  It  has  a  mesentery,  which  may  be 
long,  but  is  more  often  short,  and  the  caecum  is  com- 
pletely covered  by  peritonaeum.  It  may,  however, 
become  adherent  to  the  side  of  the  abdominal  wall, 
and  the  parietal  as  well  as  a  part  of  its  visceral  layers 
may  be  changed  to  connective  tissue ;  in  which  case 
it  would  be  only  partially  covered. 

ASCENDING  AND  DESCENDING  COLONS. 

In  the  embryo  the  ascending  and  descending 
colons  have  a  long,  free  mesentery.  They  are  quite 
movable,  and  entirely  covered  by  peritonaeum  (Fig. 
XX).  Just  before  birth  the  colon  with  its  mesentery 
becomes  adherent  to  the  posterior  parietal  perito- 
naeum. The  latter  is  changed  to  connective  tissue 
as  well  as  the  visceral  layer  on  the  posterior  surface 
of  the  mesocolon  and  colon.     In  this  way  the  colon 


TRANSVERSE  COLON.  85 

becomes  fixed  to  the  posterior  abdominal  wall,  and  is 
only  partially  covered  by  peritonaeum  (Fig.  XXI). 


TRANSVERSE   COLON. 

This,  like  the  other  portions  of  the  large  intestine, 
in  the  embryo  has  a  long  mesentery  ;  is  Yory  mov- 
able, and  is  covered  by  peritonaeum  (Fig.  XXXYI). 
Later,  after  the  development  of  the  great  omentum, 
the  visceral  peritonaeum  on  the  superior  surface  of 
the  transverse  mesocolon,  as  well  as  that  on  the  colon, 
becomes  changed  to  connective  tissue  and  adheres  to 
the  posterior  layer  of  the  great  omentum.  Its  an- 
terior surface  is  then  covered  by  the  visceral  peri- 
tonaeum of  the  posterior  layer  of  the  great  omen- 
tum. Its  posterior  surface  remains  unchanged  (Fig. 
XXXYII).  So  the  transverse  colon  at  all  periods 
of  life  is  covered  by  peritonaeum. 

SIGMOID   FLEXURE. 

The  mesentery  of  the  sigmoid  flexure  is  attached 
to  the  aorta,  and  is  usually  long  and  movable.  The 
gut  is  entirely  covered  by  peritonaeum. 


86  ANATOMY  OP  THE   PERITONJSUM. 

EEOTUM. 

The  first  portion  of  the  rectum  has  a  mesentery 
attached  to  the  median  line.  The  organ  is  entirely 
covered  by  peritonaeum.  The  posterior  visceral  peri- 
tonaeum on  the  second  portion  of  the  rectum  is 
changed  to  connective  tissue,  so  that  the  organ  be- 
comes fixed,  and  is  only  partially  covered  by  peri- 
tonaeum. The  third  portion  of  the  rectum  is  desti- 
tute of  peritoneal  covering. 

KIDNEY. 

At  all  periods  of  life  these  organs  lie  behind  the 
peritonaeum  in  the  retroperitoneal  space  (Figs.  XX, 
XXI,  and  XXXII). 

There  is  nothing  further  to  add,  as  regards  the 
relation  of  the  peritonaeum  to  the  rectum,  uterus,  and 
bladder,  than  is  given  in  the  text-books  of  anatomy. 


THE   El^D. 


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